Storm集群的DRPC模式

storm的DRPC模式的作用是实现从远程调用storm集群的计算资源，而不需要连接到集群的某一个节点。OK。那么storm实现DRPC主要是使用LinearDRPCTopologyBuilder这个类。下面就先来看看一个简单的例子，它的源码的github上。

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.LocalDRPC;
import backtype.storm.StormSubmitter;
import backtype.storm.drpc.LinearDRPCTopologyBuilder;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseBasicBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;


public class BasicDRPCTopology {
  public static class ExclaimBolt extends BaseBasicBolt {     //主要需要覆写execute方法和declareoutputfields方法
    @Override
    public void execute(Tuple tuple, BasicOutputCollector collector) {
      String input = tuple.getString(1);
      collector.emit(new Values(tuple.getValue(0), input + "!"));
    }

    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
      declarer.declare(new Fields("id", "result"));
    }

  }

  public static void main(String[] args) throws Exception {
    LinearDRPCTopologyBuilder builder = new LinearDRPCTopologyBuilder("exclamation");//实现DRPC模式
    builder.addBolt(new ExclaimBolt(), 3);

    Config conf = new Config();

    if (args == null || args.length == 0) {
      LocalDRPC drpc = new LocalDRPC();
      LocalCluster cluster = new LocalCluster();

      cluster.submitTopology("drpc-demo", conf, builder.createLocalTopology(drpc));

      for (String word : new String[]{ "hello", "goodbye" }) {
        System.out.println("Result for \"" + word + "\": " + drpc.execute("exclamation", word));
      }

      cluster.shutdown();
      drpc.shutdown();
    }
    else {
      conf.setNumWorkers(3);
      StormSubmitter.submitTopology(args[0], conf, builder.createRemoteTopology());
    }
  }
}

　　这段代码主要实现的功能是给接收到的每一个输入后面添加一个感叹号。ok，这样就可以编译提交了。

不过在这之前需要先配置storm集群的drpc server的ip。如图。主要是下面的server的ip需要配置好。并且集群的每一个节点的配置文件都需要配置这项参数！